The present invention relates generally to the field of mailing machines, and more particularly to a cassette for use in mailing machines which encloses a disposable inked ribbon used in conjunction with a thermal transfer printing process by which the mailing machine prints a postage indicia on envelopes.
Mailing machines have long been well known and are in very widespread use in virtually all commercial, professional and even home applications which involve the handling of mail. Typically, a mailing machine includes a postage meter having a printing mechanism that prints a postage indicia on an envelope that is fed through the mailing machine in any suitable manner to evidence the payment of appropriate postage for depositing the envelope with the Postal Service. For a long period of time, the traditional method of printing the indicia has been by direct ink transfer from an engraved die bearing an image of the indicia, to which ink is applied by a variety of inking devices prior to each printing operation. The dies have been either curved and mounted on a rotatable drum so that printing can take place while an envelope is moving through the mailing machine, or have been flat and mounted on a movable mechanism that presses the die against an envelope while it is momentarily held stationary in a printing position within the mailing machine. In either event, after ink is applied to the die between successive or several printing operations, the ink is transferred to the envelope by direct pressure of the die against the surface of the envelope.
While these mailing machines enjoyed great success for a long period of time, the nature of the printing mechanisms has caused these machines to be relatively complex, large and therefore expensive, with the result that relatively small offices, business organizations, and even individuals, which involve relatively small volumes of mail, cannot economically justify the purchase and installation of these machines. Accordingly, recent mailing machine technology has been directed to alternative methods of printing postage indicia on envelopes in order to substantially reduce the complexity of mailing machines, reduce their size, and therefore in these and other ways greatly diminish the cost of purchase and maintenance.
One of the methods currently under development for use in mailing machines is that of thermal transfer of ink from an ink permeated ribbon in a selected image pattern to deposit ink on the surface of an envelope in the image of a postage indicia. In its simplest form, this method involves bringing the surface of an envelope and a ribbon that is permeated with suitable thermal transfer ink into intimate contact, and moving the envelope and ribbon combination beneath a thermal print head which has the capability of heating the inked ribbon selectively along a print line so that the ink is heated and transferred to the surface of the envelope in the desired image pattern. The thermal print head includes a plurality of minute heating elements spaced along the print line which are selectively actuated under the control of suitable software so as to heat the ribbon in a precisely controlled sequence which will produce the desired image on the envelope as the envelope and ribbon are moved relative to the print head.
This method of printing in general printing applications is not new, and has proved very successful. But when applied to the printing of postage indicia on envelopes by mailing machines, several problems unique to this use become apparent. One in particular is that the ink used to print the postage indicia is uniquely formulated for the intended purpose, as a result of which the ribbons are quite expensive. In addition, once used, special security techniques must be observed to prevent unscrupulous users from attempting to reuse the ribbons to obtain duplicate postage indicias for which they have not paid, thereby lending further expense to the cost of use of these ribbons. Another factor which contributes to the high cost of the ink ribbons is the necessity of packaging them in a suitable cassette which can be inserted into and removed from the mailing machine by the user in order to facilitate easy replacement of ribbons as they are used. Thus, it is seen that, although the complexity and cost of the equipment for thermal printing in mailing machines has greatly reduced the cost thereof, a substantial portion of the savings to the user is offset by the cost of constantly purchasing new ribbon cassettes.
One major problem that raises the user's cost in purchasing new ribbon cassettes is that of breakage of the ribbon during operation of the mailing machine. The ribbons are susceptible to breaking either from an envelope jamming in the printing area, thereby stalling the tape and causing the take up spool to apply excessive tension and breaking it, or the application of too much torque on the ribbon take up spool. With currently available cassettes, if for whatever reason a ribbon breaks, the broken end cannot be reinserted into the cassette, and consequently the user must replace the cassette, thereby wasting the unused portion of the ribbon in that cassette.
Thus, it is clear that there is a need for a relatively simple, inexpensive and easy to use cassette for holding a thermal ink ribbon in the thermal printing mechanism of a mailing machine which solves these problems.